Devotion
by chasingriver
Summary: Sherlock has his first heat and tries to manipulate Mycroft into bonding with him. Things don't go according to plan. (Omegaverse: Alpha!Mycroft/Omega!Sherlock)


**A/N: **For Deklava, who asked for 'just one paragraph' in this AU. She knows me too well.

This will probably be my one-time foray into the omegaverse. I had a lot of fun writing this, but I'd rather play in my Slut!lock AU on a long-term basis.

Thanks also to Deklava for the beta.

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**Warnings: **sibling incest, omegaverse, rough sex, spanking, mild breath play. Full consent, though (no dub-con/non-con).

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Mycroft scowled when he saw the caller id light up with his brother's name. Sherlock never phoned him unless he was in trouble.

"My, can you come home? Now?" His voice sounded scared and desperate.

"Of course, Sherlock, I'll be right there. What is it?"

"I just… need help. I made a mistake."

_Oh, God._

"I'm only in the town, I'll be there in ten minutes," he said, speaking in reassuring tones.

"Thank you."

At least ten different scenarios ran through his head, none of them good. He abused the Jag, pushing it around the tight corners of the country lanes in an effort to get home faster.

The second he ran through the front door of the manor, he knew what was wrong. Omega scent permeated the air. His eighteen year old brother was having his first heat. He bolted up the main stairs with a yell, "Sherlock?"

One of the beta servants pointed down the hallway. "Your room, sir. There's been a bit of a problem."

Mycroft barely heard the man as he rushed to his bedroom. Even without the servant's guidance, he could have found his brother in the dark. Fear for his brother's safety mingled with a disconcerting arousal. There wasn't time for a suppressant patch, though. Three of the house staff, all alphas, prowled outside his bedroom door in a state of arousal and extreme agitation.

_All of them should be on patches. Someone is going to pay for this travesty._

"What the bloody hell do you think you're doing?" Mycroft bellowed.

All three stopped their pacing in surprise and turned to face him.

"How dare you! Get away from my brother. If he belongs to anyone, he belongs to me," he said with undisguised menace. "Where the hell are your patches?"

Alphas or not, Mycroft was their employer.

Their simultaneous looks of confusion told him something was off. They all fumbled behind their right ears.

"I… I'm wearing it, sir. I'm so sorry, I don't know why it didn't work," the first one spoke up, with genuine fear in his voice. The other two nodded, timidly.

"Get out of here before I do something I regret," he bellowed, and they scurried off down the hallway. "And get some new patches!" he called after them.

He silently thanked the craftsmanship of eighteenth century woodworkers; the staff had been unable to get into his room. God knows what disaster would have awaited him if they had. He pulled out his wallet and removed the small suppressant patch he kept there. He was already hard and images of his brother laid out beneath him, begging to be fucked, lurched through his mind. He had to control himself before Sherlock unlocked the door.

Sherlock's voice came through the walls. "My? Is that you? I'll get the door."

"No! Not yet, Sherlock," he shouted. "Give me a few minutes. Please." He leaned heavily against the wall with his fists clenched, waiting desperately for the drugs to counteract his seething hormones.

After a few more torturous minutes filled with visions of his brother, naked and desperate on his bed, he finally felt the overwhelming urge subside a little. The patch wasn't completely helping, but it was a start. At least he'd be able to be in the same room as Sherlock without ravaging him; the rest would be up to his own self-control.

"Alright," he said, "open the door."

Sherlock opened the massive wooden door and stood there, looking terrified.

"I'm so sorry, My."

Mycroft frowned. "Why?" He hadn't thought beyond the 'omega in first heat trapped by alphas' scenario, but Sherlock's expression changed that. _Three patches, all failing. _

Sherlock backed away from him.

"What did you do, Sherlock?" he uttered through gritted teeth as he followed his brother into the room. "Why weren't their patches working?"

"It was just an experiment, My. I wanted to see if I could alter the molecular structure of the suppressant hormone and render it temporarily ineffective." He gave Mycroft a sheepish look. "It worked. I just didn't expect it to work quite that well. I hadn't considered what would happen if you weren't home to keep the staff off of me."

"You're damned lucky I had an older patch in reserve then, aren't you, or else you wouldn't be able to keep me off of you, either. As it is, I'm just going to thrash you for being an idiot instead of fucking you so hard you wouldn't be able to stand. I'll have a beta take care of your heat with toys once I'm done punishing you."

"You don't understand, My; I just forgot to check your wallet. Why do you think I did it? You're far too considerate; far too bound by social conventions. I knew you'd put a patch on as soon as you could tell I was going into heat. I want to bond with you, that's why I did this. I just made a few miscalculations."

His alpha brain flared hot behind his eyes. _He did this to bond with me. _Even with the suppressant, that knowledge was almost enough to push him over the edge, but not quite.

"I've already told you Sherlock, that can't happen," he said through his teeth, willing himself not to snap and push Sherlock onto the bed.

"Tell me you don't _want_ it to happen, and I'll stop," Sherlock said levelly. "I'll let one of your boring little betas take care of me instead. But I think you do, My. I think you want this just as much as I do, and I see no point in getting myself bonded to some socially acceptable alpha when I have the one I want right here."

Mycroft swallowed. It was true, he did want Sherlock. The revelation that Sherlock wanted _him_ made his head spin.

Sherlock pushed his body against Mycroft's. "Well?" he drawled.

"You're just trying to kill me, aren't you?" He sat back heavily on the bed and dragged Sherlock with him.

Sherlock's eyes lit up but then Mycroft pulled him over his knees. "What are you…?" He twisted and squirmed, trying desperately to work his erection against his brother's thigh, but Mycroft's hand pressed against his lower back and held him down firmly.

He'd never punished Sherlock before; he'd left the task to less emotionally involved third parties. He hoped to dissipate some of his current lust by concentrating on his anger, but it really wasn't working.

"Do you know how irretrievably stupid that was, Sherlock? What you did? You're lucky you had somewhere to hide. One of them would have claimed you before I'd gotten back." He pulled down Sherlock's trousers and pants and let them gather around his ankles in a heap. Without hesitating, he dealt blow after blow with his palm onto his brother's pale arse.

It was five strokes before his anger subsided enough for his brain to re-engage. Seven before he realised Sherlock was moaning like a whore and rutting against his thigh. Nine before he could bring himself to look at his brother's half-naked, writhing form.

He caught one glimpse and closed his eyes as quickly as he could. The patch wasn't helping at all now.

"I can feel how hard you are, Mycroft," Sherlock purred. "You want this as much as I do."

_Oh, God._

He fixed his gaze on the far end of the room and gave him another ten vicious strokes. It didn't help matters; it just made Sherlock grind against his thigh harder and moan louder.

"Look at me, My. Look how wet I am for you. Do you know how long I've waited for this?"

Of course he knew; he'd waited just as long. He just never thought he'd allow himself to go through with it.

He finally opened his eyes and looked down at Sherlock's spanked, glowing arse. It felt almost beyond his control as he reached out and slid his fingers across his brother's entrance. They came back dripping wet. As he sucked Sherlock's natural lubrication from his fingers, his upper lip twitched involuntarily.

He pulled both hands from his brother's body. "You need to leave, Sherlock. Even I don't have this much self-control. If you stay…" he trailed off.

"You'll give me what I want?" Sherlock finished his sentence, looking back at him through half-closed eyes.

"It's not right, Sherlock. You can't give valid consent in this condition." Mycroft's defences were weakening rapidly. He wasn't even arguing whether or not they should be bonded anymore.

"You know it's not just the hormones, My; I've wanted this for years. Besides, I altered the patches long before I came into heat. If that isn't forethought, I don't know what is. It took me weeks to get that formula right."

"You'll belong to me." It was the only argument he had left.

"I already do."

The remains of Mycroft's self-control disappeared and he stood up, pushing Sherlock onto the bed. He crawled on top of him and pinned his brother's arms next to his head. "You don't know how badly I've wanted you, Sherlock," he growled and kissed him so hard his brother's whole body arched beneath him.

"I'm yours," Sherlock replied when Mycroft released his mouth.

Mycroft crawled off Sherlock's body and he whined in protest, "Come back, My."

"I'm not going anywhere. I want you over my lap; better access to that wet, eager hole of yours."

Sherlock's face went into a slack smile and he eagerly complied.

"You like following orders, don't you? It makes you feel good. Your body's wired that way, you know."

He held Sherlock firmly in place just above his arse and once again ran the fingers of his other hand across his dripping entrance.

"Taste yourself, brother," he ordered.

When Sherlock opened his mouth, Mycroft roughly pushed two slick fingers inside, stretching it open. Sherlock instinctively tried to back away, not expecting the intrusion, but Mycroft held his head in place. "It's a wonder I can think, even with a patch. Your scent is all over the room."

Sherlock's tongue glided over Mycroft's fingers as he sucked his own lubrication from them.

"You've never tasted yourself before, have you?"

He shook his head.

"See how delicious you are? You can't go out in the world unsupervised now, little brother. Every unbonded alpha for miles would be on you in a minute. For the next three days, _I'll_ give you what you need. You're going to be insatiable. You think one orgasm is going to fix this?" He rubbed his thigh against Sherlock's straining erection. "You have no idea. When you're in heat, you'll be begging for it constantly. Once won't be enough. It'll just make the need even greater."

He grabbed Sherlock's wrist and pulled it gently behind his back.

"Touch yourself. Feel how wet you are."

Sherlock moaned as his fingers danced across his tight, pink entrance.

"Have you ever fingered yourself while you masturbate?"

"No," Sherlock answered, nervously.

"I'm going to have to prepare you then; you won't be able to handle a real knotting straight off."

_It's so tempting though, _Mycroft thought._ I want to be the first thing to violate that delicious passage; to fill it up and own it. Not some toy. _

He kept Sherlock pinned across his lap as he reached into the nightstand for the knotting dildo. He'd bought it years ago, waiting for his brother's first heat. Guilt and social propriety had convinced him that it would probably be some lucky beta using it on his brother instead of him. He certainly didn't want to let Sherlock fall prey to the first random alpha that came along.

But now, Sherlock had made it clear that he'd wanted this as much as Mycroft had all these years.

"There's something I never told you, Sherlock."

His brother looked up at him from his position over Mycroft's knee. His pupils were completely blown with lust. "What?"

"The only reason I'm still unbonded is that I wanted the chance to be your first; I just never thought I'd get it. I suppose I was waiting until someone else had the honour of taking you before I gave in and settled for another omega. You're lucky I had this patch though, brother. At least we can do this slowly enough that I don't injure you."

Sherlock huffed. "If I'd gotten all the patches, you'd already be filling me with your knot. Explain to me how I'm lucky? My body can take it."

Mycroft grabbed the back of his neck, and his brother immediately fell silent and relaxed beneath his touch. "You'll take what I say you can take, Sherlock."

The knotting dildo wasn't huge, but his brother had never felt anything in his arse, let alone a knot. It would be more than adequate to prepare him. It would have to be; Sherlock's musk was driving him insane, and only the patch and sheer force of will prevented him from pushing his brother to the floor and plunging into his wet, virgin hole so hard that he'd scream. As much as he wanted to, he wouldn't; Sherlock was his brother, and he wouldn't take him until he was prepared, no matter how intoxicating his scent.

He laid the object across Sherlock's lower back as he teased Sherlock's hole open with his fingers. The first one slid in without complaint. Sherlock's natural lubrication poured out of him in a steady trickle now; his body, if not his brain, knew what was coming.

"You're doing well, Sherlock; I knew you would. Another finger now." They both sighed as he plunged a second finger into that tight, wet heat.

"Come on, My. I can take more. Stop teasing," he whined.

"Don't provoke me, Sherlock. You feel my cock jabbing you in the stomach?"

He nodded.

"It's thick; more than you can take right now. Even without my knot, I'd split you in half."

Sherlock replied with a guttural moan and writhed sinuously over Mycroft's knees. "I could take it," he persisted.

"You will, soon enough, but you need to last through three more days of this, and I'm not going to break you the first time through."

Sherlock muttered his discontent but was shocked into silence as Mycroft slid the head of the toy into his tight passage.

Mycroft chuckled, "That shut you up, didn't it?" He watched the tight ring of muscle flex and stretch around the silicone. "Look at you, so wet for it. I always thought you'd be like this. So responsive."

He slowly pushed the toy further inside. Its shaft was slightly tapered and bulbous - barely enough to notice, he imagined - before it flared out into a thick knot. After the knot, the shaft returned to its original size for a couple of inches; it would give Sherlock's arse plenty of room to close tightly around it once he finally managed to take it inside.

He slid the toy in just to the point where it started to taper. He wanted to give him a chance to adjust. Judging from Sherlock's moans, and the fact that he'd completely soaked Mycroft's trousers, it wasn't taking him long to acclimatise.

Soon Sherlock was fucking himself on the toy with abandon. Mycroft was mostly holding it in place as his brother rocked back and forth on it, moaning each time it grazed his prostate.

When he started getting mouthy again, Mycroft pushed the flared base of the knot into him, and he cried out in surprise.

"Oh, God… what…"

"That's a taste of what you're made for, little brother. Do you like how it fills you up? It's what you need, isn't it?" Mycroft shifted his thigh to stimulate Sherlock's erection; the stretch from the toy was bound to be uncomfortable at first. Filthy words and frottage would ease the way. "I wish I were in you right now, filling you for the first time with my cock instead of this toy. Do you want my knot, Sherlock? Do you want me to stretch you full and then tie with you? It'll hurt, little brother, but it will feel so good, stretching you out from the inside like that."

"Yes, My. God, yes. Do it now, please."

"I wish I could, believe me. You have to take this first. Let me fuck you with this ridiculous toy, then you can feel the thick slide of my cock up your arse."

He pushed the knot further into Sherlock's hole and his brother squirmed back, eager to take as much as he could. Mycroft fought the urge to shove it inside all at once. As wrong as it was, he wanted his brother's first screams to be from _his_ knot, not some toy.

He backed off and returned to fucking him with the shaft, which slid in and out ridiculously easily now. His own cock ached so much he wanted to scream himself.

"Have you ever had a cock in your mouth, Sherlock?" _The answer had better be no, or I'll kill the bastard who dared, _he thought to himself.

"No."

"Undress me. You're going to start learning while I work this into you. It won't be the best angle, but you'll have plenty of time in the future to hone your technique," he said dryly. Mycroft positioned him over his knee with Sherlock's head in his lap, so he'd still have access to his arse. A few seconds later, his brother's perfect lips closed around the thick head of his cock, and Mycroft almost came.

"Oh, God." Mycroft struggled for control over his brain as Sherlock's tongue learnt devastating new tricks. He finally had the wherewithal to thrust the dildo back into his brother's wet hole, and his brother's mouth fell open in a groan of pleasure. He took the opportunity to shove both his cock and the dildo in deeper than they'd been before.

Mycroft watched with fascination as his brother's arse slowly took more and more of the thick knot.

"That's it, little brother. Bear down on it. The sooner you get that in you, the sooner it'll be me, filling you up and splitting you open."

Sherlock moaned around his cock. It sounded like 'more.'

Even wearing the patch, the alpha at Mycroft's core broke through when he heard Sherlock's muffled plea. "Oh, I'll _make_ you take more," he growled. "You're going to be my fuck-toy, Sherlock, and you're going to love it. You'll beg me not to stop."

Sherlock moaned again, just noise this time.

Mycroft grabbed the back of his neck and carefully extracted his cock from between Sherlock's lips. "Very good, little brother. You're a quick study with that mouth of yours, but I'll save the delicious sight of you choking on my cock for later." Watching Sherlock take both his cock and the toy had inflamed his alpha nature beyond the limits of the patch, and Sherlock was going to get a taste of what was to come. "I don't know how much longer I can stand to wait, so I'm just going to force this toy inside you until it fits. You're already close; I know you can take it." He pushed him into position over his knees again and twisted the toy roughly back into his passage.

Sherlock bucked as the silicone slid mercilessly over his prostate, and Mycroft held him down. "Oh Sherlock," he said with a trace of pity, "it's going to get a lot more intense than that." To prove his point, he braced Sherlock's body as he bore down on him with the thick knot.

"Ah… ah… oh, fuck…" his brother gasped.

"Thick, isn't it?" Even pushing this hard, he still couldn't quite get it inside him.

Sherlock nodded, almost incoherent.

Mycroft lowered his head to Sherlock's ear, and whispered, "I'm thicker. The first time I knot you, you're going to scream."

The thought of it was all it took; Sherlock groaned as the last fraction of the toy slid inside and his arse sealed closed around it.

Seeing the toy slide home and feeling Sherlock relax across his legs tempered Mycroft's own need a little and the patch reasserted some level of control. He took a few deep breaths and managed to compose himself. It let him focus, once again, on Sherlock's emotional well-being and what they were getting themselves into.

"Good job, little brother," he murmured. "Relax so I can get this out." He rubbed the small of Sherlock's back and gently eased the toy from his passage.

He helped his brother to his feet and motioned to the bed beside him. Sherlock sat down and looked at him, expectantly.

"I want there to be no misunderstandings about this. Do you want me to bond with you, or do you just want me to be your first? Either is acceptable." _One will break my heart, but it's acceptable. _

"I want to you to bond with me, Mycroft. I want to be yours."

"You understand this means you'll never bear children?"

Sherlock nodded; biological mechanics were taught in school from a young age. Familial bondings were the ultimate insult to biology; in a world where omegas existed mainly to breed children, cell incompatibility between siblings ensured the omega would never get pregnant. This flagrant disregard for procreation fuelled the backlash against sibling bondings, and they were regarded with even more disgust than the brave omegas who took birth control.

"I don't want children, My. I want _you_."

Mycroft beamed, and kissed him.

"Thank you, little brother. Are you ready? Because once I take this off, you won't be going anywhere for the next three days."

Sherlock nodded.

Mycroft let out a long, shuddering breath, and peeled off the patch that had been holding him at bay. The rush of hormones flooded his brain and threatened to overwhelm him; there was no possibility of discussion now, and he didn't want one. He wanted one thing.

"Lean against the wall, Sherlock," he growled.

Sherlock braced himself against the wall and spread his legs. Mycroft reached between them and cupped his balls.

"You're mine," he muttered. He spread Sherlock's cheeks and his mouth watered at the sight of his brother's gaping, wet hole.

"I'm ready, My," Sherlock breathed.

It didn't much matter if Sherlock was ready or not. At this point, there was little Mycroft could do to control his instincts. He swiped his hand across the slick fluid coating Sherlock's balls and thighs, and smeared it across his engorged cock.

His brother groaned, "Please, now…"

Even as the words left his mouth, Mycroft lined up and plunged into him, deep and hard, in one swift stroke.

"Yes!" Sherlock howled.

The primal sound served to excite Mycroft even further and he started pounding him without mercy. Sherlock eagerly pushed back to meet each thrust, his body trembling with a mixture of pleasure and need.

"God, My. I've wanted this for so long," he panted as he braced himself against the wall.

"You have no idea," Mycroft growled.

"Can feel you… so deep. At my core," Sherlock muttered, almost incoherent with bliss.

"So much better than a toy, hm? You were made for this; you fit me so perfectly." He angled his thrusts to hit Sherlock's prostate more directly, and his brother twisted in his grasp, trying to escape the intensity of it. Mycroft removed one hand from Sherlock's thigh and roughly grabbed the back of his brother's neck. "Take it, Sherlock. You'll take everything I give you and beg for more." The firm hold immediately made Sherlock more submissive and his incoherent moans quieted somewhat.

"Yes," Mycroft purred, "now you understand what it means to be an omega? What it means to submit and let someone else take charge of your pleasure? You'll never be content with a solitary wank again. This is what you need; to be taken and owned and cherished like the prize you are." Mycroft released Sherlock's neck to get a better grasp on his brother's hips as he kept up his brutal pace.

Sherlock gave up trying to brace himself with his wrists and fell forward onto his forearms. He rested the top of his head against the tastefully painted wall and gave himself over to it, letting Mycroft fuck him as hard as they both wanted. The force of it shook the picture hanging next to the bed - the two of them as children; Mycroft's arm wrapped protectively around Sherlock's smaller frame.

Sherlock, more sturdy with his body in the new position, dropped one hand to stroke his cock.

Mycroft batted it away. "No. You're not coming before I knot you." The first time would be uncomfortable, and the bleeding edge of arousal would raise his brother's tolerance for pain. Besides, he needed to learn his place. He might be more lenient with him in the future, but to do it now would set a dangerous precedent. Even as an omega, Sherlock had the dominant pushiness inherent in a Holmes.

Sherlock whined, "M'close, My. Please…"

Mycroft wrapped one arm across Sherlock's chest and pulled him closer.

Sherlock writhed against him, begging for more.

"God, you're insatiable," Mycroft muttered as he drew out and plunged back in. "Utterly perfect."

As Mycroft got close to knotting, the base of his cock got thicker and Sherlock started to squirm again.

"Oh, oh… I don't know if… oh," he gasped.

"You can take it, Sherlock; your body was built for this. Once you get a taste of my knot stretching you out, you won't want anything else."

Sherlock moaned, almost beside himself with lust, and dropped his hand to stroke himself again. Mycroft moved his arm up Sherlock's chest and grasped his throat. "I said no," he growled as he tightened his grip and restricted Sherlock's oxygen. His brother leaned into it, pressing against Mycroft's hand for more. Mycroft smiled. _Trust him to enjoy it_, he thought. He tightened his grasp just to the point of pain, and Sherlock dropped his head in submission. Mycroft released his hold and dragged his fingernails down Sherlock's back, watching with satisfaction as his body arched into the sensation.

Mycroft's whole body thrummed with electricity; he was so close now, and he pulled Sherlock completely away from the wall and held him tightly to his chest. With a final, vicious thrust, he buried himself inside Sherlock. He sank his teeth into his brother's shoulder, and the consummation of their bond sent him over the edge; he felt the tension in his gut release and he groaned as the heat tore through him and his knot formed.

Sherlock groaned with pleasure as Mycroft marked him and it turned into a lustful scream as the thick knot plugged his arse and filled him in ways even the toy hadn't prepared him for. The pressure on his prostate combined with the obscene stretch of it was more than his overloaded senses could handle; he came hard, shuddering and gasping and squirming at the still-unfamiliar intrusion.

Mycroft held him tighter and licked the mark on his shoulder. The taste of blood sealed their bond, and he came at the thought of it, emptying himself deep inside Sherlock. The orgasm ripped through him, prolonged by powerful omega muscles milking his cock dry.

They were still bound together by his knot, so Mycroft lifted Sherlock and carried him the few steps to the bed. He gently placed his brother on it and curled his joined body protectively around his. As they came down from their hormone-induced high, he asked, "Are you alright, Sherlock? Did I hurt you at all?"

"Mm, I'm fine," he answered contentedly, but his eyes sparkled with the excitement of new discoveries. "It was uncomfortable at times, but it was good - like I pushed my body to its limit and realised it could go further than I thought. The stretch of it made me ache so much, My, but in all the right ways. The pain of it just fed the pleasure, if that makes sense."

Mycroft smiled and kissed the base of Sherlock's neck. It was still damp with sweat from their exertion. "Yes, little brother. It does." He pulled back to look at the bite mark he'd left on his shoulder. He touched it gently; it had barely broken the skin - just enough for a few drops of blood - but it was enough.

"Bonded for life," Sherlock said, with a trace of uncharacteristic awe in his voice.

"Yes, Sherlock. Thank you. I always wanted this; I just didn't know you did."

Mycroft's cock had softened enough to slip out of him, and Sherlock shifted to face his brother.

"I did, and I'm glad," Sherlock said, and kissed his brother, taking the opportunity to explore and catalogue his mouth now that the urgency was gone.

Mycroft leaned into it and sighed contentedly as they kissed. He wrapped his arms around Sherlock again and pulled him closer.

"You realise you're going to have to come and stay with me in London when you're in heat," he said.

Sherlock gave him a small smile. "I know," he replied. "I was sort of hoping I could move in with you; perhaps I could go to university in London instead of Cambridge." Then he frowned. "Are there going to be repercussions for this? For you at work, I mean."

"I'll handle that, Sherlock," he said gently. "Besides, I have enough influence now that I don't believe it will be a problem. I'll take care of you, don't worry."

"Mm, alright," Sherlock nodded and curled up against the warm skin of his brother's chest.

Mycroft pulled a blanket over them and smiled. It wouldn't be long - an hour, perhaps, at most - before Sherlock and his omega libido were begging for more, but there was nothing wrong with a good doze before they started in on the next round.


End file.
